Standards & Successes Emerge

Madanmohan Rao kicks off a new regular feature that delves into the brave new world of industrial wireless technology.

A number of case studies of successful industrial automation design and implementation are emerging in the fi eld of intelligent embedded wireless sensor network (WSN) solutions.

The push of wireless innovation is opening up potential and possibilities that could not have been explored as envisaged in the wired world. Target environments include oil refi neries, food processing plants, wastewater facilities, pharmaceutical plants, power plants, and other locations.

Wireless sensor networking draws upon the IEEE 802.15.4 standard for self-sensing, self-healing networks. Ideally, industry implementations involve a mix of wired and wireless implementations, to allow for a balance of flexible monitoring and critical-process reliability. Key technical features of successful wireless sensor networks include frequency hopping, time synchronization, full-mesh routing and security.

Advantages & applications

The advantages over wired solutions are obvious: less cost of installation, automatic reconfi guration, more industrial safety, and ease of maintenance, according to Steve Toteda, Vice President at Dust Networks.

Regulations are requiring more measurements at more frequent intervals to ensure compliance. Specifi cally, wireless devices could be used to monitor when a relief valve opens or when there is a failure of a rupture disk. Wireless devices will provide an easy way to audit the required measurements without extensive modifi cations to existing control systems and plant wiring.

As energy prices rise, it becomes increasingly important to limit the amount of energy wasted. Plants often have many steam traps and these can be easily monitored for unusual steam flows allowing immediate correction of faulty operation that might otherwise go unnoticed for some time.

Beyond process monitoring, wireless devices are a natural fit to provide a cost-effective means for health safety and environmental monitoring. Many plants require numerous gas detectors placed throughout the plant to ensure that the air is safe to breathe and to work in. Wireless detectors will not only provide an efficient means of providing an alert to operations but also to monitor the operational status of the devices. The quality of any liquid or gas leaving a process facility is vitally important to maintaining the quality of the environment.

The worldwide market for wireless communication in industrial is expected to grow 26 percent a year over the next fi ve years, according to research from the ARC Advisory Group. And by 2011, says ON World Research, industrial wireless sensor networking systems and services is expected to account for a market worth US$4.6 billion.

But challenges arise in ensuring communication bandwidth and long battery life of remote devices. Other sectoral roadblocks have included slow progress on the emergence of industry standards – but that is starting to change.

The HART way

Standards organizations have been an important lever in this market, such as HART Communication, a global standard for smart process instrumentation which has an installed base of more than 24 million devices worldwide.

The HART Communication Foundation (HCF), which provides worldwide support for application of HART technology, recently released the HART 7 specification, enabling many new capabilities for communication with intelligent fi eld devices, including WirelessHART.

HCF has hosted public displays of Wireless and HART technology in action in events like the Hannover Fair 2007 in Germany and the recent ISA Expo 2007 in Houston. It expects WirelessHART products to become available late 2007 or early 2008.

WirelessHART instruments provide the same level of remote process and diagnostic information as the hardwired (4-20 mA loop) versions. It is the independence from the hardwired infrastructure which offers greater flexibility when compared to the traditional installation.

Migration from wired to wireless solutions is not too difficult: the wireless adapter is designed to retrofit any existing HART device and provides wireless access to both the primary process variable and all the digital data from the device.

Typical examples of WirelessHART environments include multivariable instruments, tank level gauging, environmental monitoring and steam traps. Refi nery HART implementations include the PPG Industries’ Lake Charles facility in Louisiana.

“We are beginning a new project to connect those tanks wirelessly with backup level. We also have hundreds of valves that we’d like to have positioner information on, as well as other pressures and temperatures,” says Marty Gering, wireless data collection coordinator and wireless worker administrator for the refinery.

“The low cost of installing WirelessHART will result in the enduser being able to install short-term or ad hoc process measurements to improve the view of the process, perhaps to solve quality issues,” predicts Gareth Johnston, a fi eldbus communication specialist with ABB.

“WirelessHART communication will not replace wired HART, but it will offer access to diagnostic features of fi eld devices and will allow additional applications not possible with wired devices,” observes Guido Stephan of Siemens.

Smart Dust

A major player in the wireless space is Dust Networks, which has helped develop time synchronized mesh networking protocol (TSMP), a foundational building block of the WirelessHART standard. TSMP is a set of technologies and protocols that promote open standards enabling interoperability of WSN devices.

The SmartMesh IA-510 platform assures multi-vendor interoperability and a future-proof roadmap. It provides for secure 128-bit encryption with dynamic keys. Embedded network management delivers dynamic network optimization and intelligent routing.

Dust Networks’ SmartMesh-XT family of products consists of motes and managers in both the 900 MHz and 2.4 GHz bands. The 900 MHz products include the M1030 mote and PM1230 embedded manager, and the 2.4 GHz standards-based products – which use IEEE 802.15.4 radios – include the M2135 mote and PM2130 embedded manager.

TSMP can ride on top of standard, off-the-shelf radio chips Every “mote” in a TSMP-based network acts as a router, enabling simplified network installation and extremely high reliability.

In addition to reliability and low-power consumption necessary for the industrial and building automation markets, such WSN technologies expedite the design-in process for rapid customer adoption, according to Joy Weiss, CEO of Dust Networks.

“Manufacturers in the process industries require high reliability from wireless measurement systems,” says Harry Forbes, Senior Analyst from ARC Advisory Group. Plant experience with wireless fi eld devices has shown that full mesh network layers like TSMP, while still being standardized, have outperformed other network technologies in terms of reliability and applicability to real-world commercial and industrial applications.

The available market for wireless is roughly 60-80 percent of today’s process field devices, and reliable networks like TSMP will make this possible, Forbes predicts.

Emerson Process Management uses Dust Networks’ TSMP protocol in its new in-plant Smart Wireless fi eld networks and solutions. “Self-organizing mesh networking is one of the most exciting innovations to come along in the process industry in over 30 years,” according to Steve Sonnenberg, president of Emerson’s Rosemount division.

Critical developments

“The widespread adoption of wireless sensor networks in the industrial market is dependent upon two critical developments: high reliability levels, and emerging consensus on industry standards,” predicts Mareca Hatler, Director of Research at ON World.

Proper network implementation using wireless components involves, of course, a signifi cant degree of up-front planning. It is recommended that implementation and design teams first conduct a thorough audit of physical layout, security and operational maintenance considerations.

Ultimately, such wireless solutions can “unchain” the valuable diagnostic and process data locked inside existing systems and provide for future expansion with a choice of wired or wireless field devices.

Madanmohan Rao

IA-510

TSMP